Method and apparatus for forming and tempering tubular glass flares



w. A. BOYCE 3,155,481 METHOD AND APPARATUS FOR FORMING AND TEMPERINGNov. 3, 1964 TUBULAR GLASS FLARES 2 Sheets-Sheet 1 Original Filed Dec.27, 1954 TEMPER/A G' INVENTOR. W/urme r7. BOYCE BY! Nov. 3, 1964 W. A.BOYCE METHOD AND APPARATUS FOR FORMING AND TEMPERING Original Filed Dec.27, 1954 TUBULAR GLASS FLARES 2 Sheets-Sheet 2 United States Patent M3,155,481 METHOD AND APPARATUS FOR FORMING AND TEMPERHNG TUBULAR GLASSFLARES Walter A. Boyce, West Grange, N.J., assignor to WestinghouseEiectric Corporation, East Pittsburgh, Pa., a corporation ofPennsylvania Continuation of application Scr. No. 477,687, Dec. 27,1954. This application July 3, 1958, Ser. No. 746,557 7 (Ilaims. (Cl.65-104) This invention relates to the manufacture of glass flares and,more particularly, to an improved method for making flares used in themanufacture of stems for lamps and electronic tubes. This application isa continuation of application Serial No. 477,687, filed December 27,1954, now abandoned, entitled Manufacture of Glass Flares, and owned bythe assignee of the instant application.

Heretofore it has been the universal practice to manufacture flares byheating the end of a length of glass tubing to plasticity, forming thesoft glass into a flange, and then allowing the glass to cool freelyuntil it was no longer plastic before gauging and cutting a section ofthe desired length from the tubing. Such sections of glass tubing havinga flange formed on one end are known 'as flares and are used in aconsiderable range of lengths and sizes in the lamp and tube industry.It has been found that flares manufactured by the foregoing method havea strong tendency to break while being handled or to fracture during thesubsequent sealing-in operation. Losses arising from such breakage havebeen considered unavoidable in the past due to the inherent fragility ofthe flares, particularly the frequent inability of the flanged portionthereof to withstand the thermal shock imparted to the glass by thesudden application of heat required to properly seal the flare to theglass envelope. While the breakage of the flares themselves constituteda loss in terms of labor and material, their cost in comparison to thevalue of the component parts which has to be discarded when the flarecracked during the more advanced stages of manufacture, such as duringthe sealing-in operation, was negligible.

It is, accordingly, the general objectof the present invention to avoidand overcome the foregoing and other deficiencies of the prior art byproviding a method of manufacturing glass flares which are uniform insize and shape and not easily broken or cracked.

Another object is to provide a simple economic means of controlling themechanical and thermal shock resistant properties imparted to glassflares during their manufacture.

A still further and more specific object is to provide a method ofimparting a predetermined stress pattern to the structure of glassflares during the normal sequence of operations required to manufacturethem such that the mechanical and thermal shock resistant properties ofthe flanged portions thereof are materially improved.

The aforesaid objects of the invention, and other objects which willbecome apparent as the description proceeds, are achieved by controllingthe heat applied to the end of the glass tube prior to theflange-forming operation, by providing means for rapidly and uniformlycooling the flanged and adjacent tubular portions of the tube to atemperature well below the strain point of the glass immediately afterthe flange has'been formed from the soft glass, and by controlling theapplication of the cooling medium to prevent distorting the contour ofthe'hot flange.

Specifically, the abrupt cooling of the. glass from its plastic state toa temperature below its strain point tempers or hardens the surfacesthereofand increases the resistance of the flanged portionof the flareto mechanical or thermal shock. This improvement in the 3,155,481Patented Nov. 3, 1964 "shock resistant properties of this portion of theflare is obtained by imparting to the glass a predetermined stresspattern whereby the surface layers thereof are under compression andheld in equilibrium by an interior region which is in tension. Thecompressive strength of glass member, such as by heating the glass to atemperature well above its annealing point and then suddenly applying :acooling medium to reduce the temperature below the strain point, greatlyincreases the ultimate strength of the member. In the present inventionit has been found that by increasing the heat applied to the end of theglass tubing prior to the flange-forming openation on a conventionalautomatic flare machine, the temperature of the glass after the flangehas been formed is such that a sudden cooling thereof tempers thisportion of the flare and greatly improves the strength of the finishedproduct without causing deleterious distortions thereof.

Further, means for cooling the flanged and adjacent tubular portions ofthe tubing can be readily incorponated into automatic flare-makingmachines now in use by providing nozzles so shaped and arranged thatwhen connected to a pressurized supply of a suitable cooling -medium,such as compressed :air, a stream of the cooling medium is ejected fromsaid nozzles at a predetermined velocity and impinges on the flangedsurfaces of the tubing immediately after the flange has been formed fromthe soft glass in a manner such that the glass is rapidly 'anduniformlycooled without distorting the shape or flare-making machine showing thevarious steps in the manufacture of :a glass flare and the location ofthe cooling or tempering station in relation to the normal sequence ofoperations;

FIG. 2 is a fragmentary elevational View, partly in section, of theflange-forming mechanism and rotating chuck assembly at station 2 inFIG. 1, taken along the line IIII in the direction of the arrows;

FIG. 3 is fragmentary side elevational view, partly in section, of thetempering apparatus. and rotating chuck assembly at station 3 in FIG. 1,taken along the line Ill-Ill in the direction of the :arrows;

FIG. 4 is a fragmentary end elevational view, partly in section, of theupper portion of the cooling apparatus employed at the temperingstation, shown in FIG. 3, taken along the line IV1V in the direction ofthe arrows,

showing the rotating chuck assembly and the location of the nozzles inrelation to the flange;

FIGS. 5 and 7 are plan views of a tempered and nor- -mal flarerespectively, showing the radial strain pattern applicable to othermethods of manufacturing flares, the

invention is usually employed in conjunction with an automaticflare-making machine and hence it has been so illustrated and will be sodescribed.

Referring now to the form of the invention illustrated in theaccompanying drawings, the portion of the rotating chuck 14 shown inFIG. 2 is representative of one of a series of chucks generally employedin a conventional automatic flare-making machine of the type describedin United States Patent No. 1,546,353. In the machine herein shown eightof said chucks 14 are equidistantly mounted around the periphery of acircular table or rotor 11 and intermittently advanced or indexed in acounter-clockwise direction, as viewed in FIG. 1, through eight stationsby means and in the manner described in the aforementioned patent. Alength of glass tubing 19 is inserted into each of the chucks 14 andsecurely held as the chuck is advanced through the first three of theabove-mentioned stations. At the fourth station the chuck mechanism isreleased and a predetermined portion of the tubing is fed through thechuck thereby gauging the length of the finished flare. Hence, after aflare is completed and cut from the tubing, the end of said tubing is inposition for the formation of the next flare. In addition to revolvingcounterclockwise with the rotor, as viewed in FIG. 1, each chuck isrotated clockwise about its own axis, as indicated by the arrows inFIGS. 2 and 3, so that each length of glass tubing therein is rotatedabout its longitudinal axis. At each of the several stations the end ofthe glass tubing 10 is subjected to the different operations involved inthe making of a flare so that after the table or rotor 11 has completedone revolution, the required sequence of operations have been performed.

The sequence of operations followed in accordance with this invention isshown in FIG. 1. At station 1, the end of the rotating glass tubing 10is preheated by means of gas burners and prepared for the flangingoperation. It is important that the glass be heated uniformly and to theproper temperature at this stage otherwise the glass may chip or adhereto the reamer during the flanging operation, or the flange will beimproperly tempered and susceptible to fracture. When the glass has beenheated to the proper temperature, as for example at least 200 C. abovethe softening point of the glass, rotor 11 is automatically advanced tostation 2 where the application of heat is continued and a flange isformed or spun on the end of the glass tubing 10 by means of a rotatingreamer or pencil which wipes the soft glass into a flange of the desiredshape and diameter. According to this invention, after the flange hasbeen formed, the glass tubing 10 is advanced to station 3 where the hotglass is force cooled to a temperature below its strain point throughthe application of a compressed air stream thereby tempering the flangedtube end. The pressure of the applied air stream must be carefullycontrolled; too great a pressure may deform the soft glass during theinitial cooling period thereby distorting the contour or size of thefinished flare, while insuflicient pressure will not cool the glassrapidly enough to impart the desired stress pattern to the flare therebydeleteriously affecting its ultimate strength. In prior art practice,the hot glass was permitted to cool at a normal rate for the solepurpose of allowing the glass to set or become sufficiently hard inorder to prevent distorting the flange during the gauging operationwhich followed. Moreover, it was believed, prior to this invention, thatsubjecting the glass to a sudden temperature change at this point wouldcause it to fracture or introduce thermal strains which would weaken thefinished flare and render it more susceptible to fracture.

At station 4, the chuck is loosened and the glass tubing 10 permitted todrop a predetermined distance thereby gauging the length of the finishedflare. Following th s, the tubing is marked or prepared for cutting bygradually building up heat in the glass at the point selected forcut-off by properly positioning gas burners at stations 5, 6 and 7. Atstation 8 a pair of cutting wheels cooperate to cut the flanged-end fromthe tubing and the completed flare is discharged into a suitably placedcontainer by means of a chute 15. The rotating chuck 14 is then indexedto station 1 and the foregoing cycle of operations is repeated. Thissequence of operations, with the exception of the tempering process andmodifications hereinbefore noted, is well known in the art and may beaccomplished by means such as those described in the above-mentionedpatent. The essence of this invention resides in the manner in which theflares are tempered during the normal sequence of operations required tomanufacture them and in the cooling apparatus employed to eifect thetempering and these are hereinafter more fully described.

After the lower end of the glass tubing 10 has been properly heated atstation 1 as previously described, the chuck 14 is advanced to station 2where a flange 12 is formed or spun on the end of said tubing 10. Ingeneral, the flange-forming operation consists of inserting a suitableflanging mechanism into the heated tube end and thereafter activatingsaid mechanism so that the soft glass wall is molded or spun radiallyoutward from its vertical position thereby forming a flange 12. Whilevarious means may be utilized to accomplish this result, the form of theinvention illustrated employs a reamer or pencil 18 which is insertedinto the end of the glass tubing 10 while in a substantially verticalposition, as indicated by the broken lines in FIG. 2, and thereafterrevolved and progressively tilted outwardly to an almost horizontalposition, as shown by the solid lines, thereby wiping or spinning thesoft glass radially outward with respect to the axis of the tubing 10and forming a flange 12 of the desired shape and diameter on the end ofsaid tubing.

The pencil 18 is activated by a flanging mechanism which, brieflystated, comprises a hollow tubular member 22 rotatably secured to astationary part of the machine by means of a bearing collar 24 andstandard 26. An elevating tube 28 disposed in telescope reciprocablerelation within the aforesaid tubular member 22 cooperates, in a mannerhereinafter more fully described, with a stirrup 20 and pencil 18assembly pivotally attached to a pair of connecting links 19 hingedlyfastened to a cap 21 mounted on the end of said elevating tube toprogressively tilt said pencil 18 away from its normal vertical positionwhen said elevating tube is longitudinally displaced as by a cam (notshown). A cap 23 secured to the end of the tubular member 22 carries apin 25 which rides within an aperture provided in the cap 21 therebycoupling said tubular member and elevating tube 28 together with respectto rotational displacement. The stirrup 20 is pivotally coupled to theupper ends of a pair of standards 13 attached to the cap 23 whichstandards straddle the end of the glass tubing 10 so as to enable thepencil 18, which is secured to a horizontal cross-member of saidstirrup, to be inserted into the tubing and said stirrup to swing onsaid standards. The tubular member 22 and elevating tube 28 are sopositioned and held by the bearing collar 24 that they are in axialalignment with the chuck 14 and glass tubing 10 and are free to move ina longitudinal direction. A thrust ball race 27 carried by a flange 29on the lower end of tubular member 22 takes up the thrust between theflange 29 and an adjustable stop 31 mounted on the collar 24 when saidtubular member 22 is elevated against said stop. Elevating tube 28 isrotated in a counter-clockwise direction, as indicated by the arrow inFIG. 2, by means of a pulley 30 attached thereto which is driven by abelt 32 coupled to a motor (not shown). A helical spring 33 interposedbetween the pulley 30 and flange 29 keeps the thrust ball race 27 andtubular member 22 normally raised with respect to said pulley 30 andelevating tube 28. The rotative motion imparted to the elevating tube 28is transmitted to the tubular member 22 and standards 13 mounted thereonby the pin and aperture arrangement above-described. Any upwarddisplacement of the elevating tube 28 with respect to tubular member 22is likewise transmitted to the connecting links 19 by the cap 21 therebycausing the stirrup 20 to swing on the standards 13 and tilt the lowerend of the pencil 18 outwardly from a vertical to a nearly horizontalposition.

Hence, when the elevating tube 28 is gradually displaced upwardly by thecam (not shown) the pulley 30 is raised thus partially compressing thespring 33 and forcing the thrust ball race 27 and tubular member 22upward until said ball race seats against the stop 31 whereupon theupward movement of the tubular member 22 ceases. The elevating tube 28,however, continues to move upwardly by virtue of further compression ofthe spring 33 until said spring is compressed flat, as shown in FIG. 2.The upward movement of the tubular member 22 inserts the pencil 18 intothe lower end of the glass tubing 10, as indicated by the broken linesin FIG. 2, whereas the further upward movement of the elevating tube 28after the upward travel of said member 22 has been stopped causes thestirrup 20 to pivot about the standards 13 and progressively swing thepencil 18 through the successive angular positions required to form theflange 12 from the soft glass on the end of the tubing and to finallyassume the position shown by the solid lines in FIG. 2. The elevatingtube 28 is then permitted to drop causing the pencil 18 to return to itsnormal vertical position, whereupon the tubular member 22 movesdownwardly thereby extracting the flanging mechanism from the flangedtube end.

Immediately after the flange 12 is formed on the preheated end of theglass tubing 10 by the wiping action of the rotating pencil 18 and theflanging mechanism is Withdrawn, the rotating chuck 14 is advanced tostation 3 where, in accordance with this invention, the glass is quicklycooled as shown in FIG. 3. While various means may be utilized to coolthe hot glass, a preferred embodiment of the invention employs twonozzles 34 and 35 having tip portions contoured to provide substantiallyslot-like outlet orifices. Said nozzles and orifices are oriented so asto lie in the same vertical plane, one above the other (as viewed inFIGS. 3 and 4), with the lip of the nozzle 35 substantially parallel tothe horizontal plane containing the rim of the flange 12, and separatedtherefrom by a distance d In order to achieve the maximum cooling ofboth the upper and lower surfaces of the flange 12 without distortingthe soft glass, nozzle 34 is mounted above and opposite nozzle 35 insuch a position that the angle defined by the orifice lips is approximately 60, as illustrated in FIG. 3. Thus, the cooling medium isdispensed by the nozzles 34 and 35 in a substantially uniplanar streamthrough which the rotating flange 12 passes, thereby effecting a rapiduniform cooling of the hot glass without deformation.

FIG. 4 is an end view of a portion of the tempering apparatusillustrated in FIG. 3 showing the uniplanar vertical positioning of thenozzles 34 and 35 and their location in relation to the flange 12 in thehorizontal direction. In order to prevent the reflection of thecompressed air stream from the glass surfaces into the machine proper,where it would interfere with the glassworking fires, it has been founddesirable to ofiset the vnozzles 34 and 35 just to the right of the axisof the nozzles 34 and 35, as viewed in FIG. 4.

Returning to the showing of the cooling apparatus in FIG. 3, the nozzles34 and35 are connected to a suitable source of pressurized coolingmedium, such as compressed air, by meansxof conduits 36. In order tocontrol the velocity'of the cooling medium and thus preventdistortion'of the hot flange 12 during the cooling process,

a regulating valve 40 and a four-way connector 37 having a pressuregauge 38 mounted thereon are provided in the aforesaid conduit means,said gauge being desirably positioned within visible range of said valve40 so that the line pressure or rate of flow of the cooling medium maybe conveniently and accurately controlled.

Experience has shown that impurities in the high-pressure air supply maybe deposited on the surfaces of the flange 12 and glass tubing 10 duringthe tempering operation, subsequently contaminating the atmosphere ofthe finished lamp and deleteriously alfecting the quality thereof. Thisis particularly true of oil and water which condense on the inner wallsof the cool air line and are later ejected and deposited on said glasssurfaces. It has been found desirable, therefore, to provide a filter42, to remove oil, water and other such impurities from the air supply.In addition, a stop valve 44 may be provided to isolate the temperingapparatus from the compressed air supply whenever necessary. Theconduits 36 are preferably fabricated from copper or similar material sothat they are substantially rigid thereby facilitating the properpositioning of nozzles 34 and 35.

From the foregoing it will be seen that air from a compressed air supplyenters the filter 42 at a substantially hig i pressure, such as at least30' p.s.i., when the stop valve 44 is open, said filter 42 removingimpurities, particularly oil and water, from said air which then passesthrough the regulating valve 40, where the pressure of said air islimited to some predetermined value. The air then passes through thefour-way connector 37, actuates the pressure gauge 38, and flows alongtwo separate branches until it is forcibly ejected through the slot-likeorifices of the nozzles 34 and 35 at a velocity determined by saidregulating valve 40, thereby impinging on the upper and lower surfacesof the hot rotating flange 12 on the end of the glass tubing 10 andrapidly cooling said surfaces at a uniform rate.

It is generally known that a glass fracture always originates at anexposed surface from a tension strain imparted to the glass whichexceeds the ultimate strength of the member. In a glass flare thetension strain may be imparted by mechanical shock or a suddentemperature change. In particular, the laterally protruding or flangedportion 12 of the flare is, by its nature, most frequently exposed tomechanical shock during handling and thermal shock during the subsequentsealing-in operation. Thus, it is generally the flanged portion 12 whichcracks during handling or subsequent lamp manufacturing operations.

However, when the hot flange 12 and adjacent tubular portion of theglass tubing 10 is suddenly cooled, as hereinbefore described, a strongcompression stress is introduced the outer layers thereof. Thiscompressive layer, in effect, hardens or tempers the glass structure andincreases the ultimate strength of the flangesince subsequent tensionstresses applied to the glass as a result of mechanical or thermalshocks must first overcome or neutralize the surface compression beforesufiicient tension strains can develop to materially weaken or fracturethe glass.

FIGS. 5 and 7 are plan views, respectively, of a flare tempered inaccordance with this invent-ionand of a flare normally cooled inaccordance with prior art practice, showing the radial stress patternstypical of flares so 'treated. In general, the configuration of theradial stress pattern typical of a properly tempered flange 12, asillustrated in FIG. 5, consists of two mutually contiguous andconcentric zones or belts surrounding the tubular section 10 of theflare. Immediately ady'acent to said tubular section 10 is asubstantially wide zone 46 which represents an area of tension, as forexample 18 kilograms per square centimeter. The second zone 48 extendsto the periphery of the flange 12. and represents a region ofcompression, as for example 36 kilograms per sq. centimeter.

Conversely, the configuration of-the radial stress pattern typical offlares normally cooled in accordance with the prior art practiceindicates a radical difference in the stress relationship When theflange 12 is permitted to cool gradually. Here, the inner zone oftension 54 is materially reduced in area While the outermost zone ofcompression 56 has increased by extending further inwardly asillustrated in FIG. 7. Hence, it would appear from the foregoing that asthe glass gradually cools the outermost compressive zone slowlyprogresses inwardly, effectively compacting the zone of tension into anarea immediately surrounding the base of the tubular section 10. Thesepatterns, however, merely represent the distribution of radial stressesin the flange 12 necessary to equalize the forces imparted to the glassunder the different longitudinal stress conditions developed within theglass structure of the flange itself and, as such, do not strengthen theflange per se.

FIGS. 6 and 8, on the other hand, illustrate the essential differencebetween a tempered and untempered flare respectively. FIG. 6 representsa lingitudinal sectional view of a flange 12 and an adjacent portion ofthe tubular section 10 tempered in accordance with this invention andillustrates the longitudinal stress pattern imparted to the glassstructure. The intermediate portion or core 50 of the glass Wallcomprising the flange 12 and the adjacent tubular portion of the flareis in tension and held in equilibrium by the equal and oppositecompressive force of the outer layers 52 which completely envelope saidcore 50. In a properly tempered flare the compressive force is at least75 kilograms per square centimeter. A similar view of an untemperedflare shows that the glass comprising the flange 12 and adjacent portionof the tubular section 10 is substantially devoid of such stresses, asshown by FIG. 8, and consequently lacks the fortification afforded bythe aforementioned compressive sheath 52.

The desired stress pattern can only be imparted to the glass structureof the flange by heating the glass to the proper temperature prior tothe flange-forming operation and by controlling the application of thecooling medium during the tempering process. These factors are criticalby virtue of the fact that the temperature of the glass prior to coolingcoupled with the rate of cooling determine the stress pattern andultimate strength of the flanged portion of the flare. Furthermore, thecooling medium must be so controlled that all surfaces of the flange arecooled at the same rate without deforming the soft glass during theinitial cooling stage. The majority of flares are manufactured from soflead type glass. A typical lead glass composition is approximately asfollows: 68% silica, 15% lead oxide, 10% soda, 6% potash, and 1% lime.Glass of this type has a working point of 975 C., a softening point ofapproximately 630 C., and a strain point of about 400 C. Hence, forflares manufactured from this type glass the end of the glass tubing 10must be heated to at least 830 C., prior to the flange-forming operationin order that the glass remain at a sufficiently high temperature, asfor example 800 C., after said flanging operation, to permit the desiredstress pattern to be imparted to the glass structure by the temperingprocess.

In addition, to obtain the proper rate and uniformity of cooling it hasbeen found desirable to position the nozzles 34 and 35 as hereinbeforedescribed so that the lip of the lower nozzle 35 is separated from theplane containing the rim of the flange 12 by a distance a such asbetween /s to A of an inch, as shown in FIG. 3. Similarly, it has beenfound that offsetting the nozzles 34 and 35 in the horizontal directionwith respect to the axis of the glass tubing 10 (FIG. 4) so that theirrespective center lines are separated by a distance d such as between Ato /2", provides the desired cooling effect and deflects the air streamout of the machine thereby eliminating adverse effects of such air onthe glass-working fires. In order to prevent distortion of the softglass during th initial cooling of the flange 12, it has been found thatan air pressure of not more than 5 lbs. per sq. inch should be used fora flare manufactured from A" tubing and having a flange spread ordiameter of approximately 7 For larger flares the air pressure must beincreased due to the larger amount of heat which must be extracted. Forexample, to properly cool a flange A" in diameter formed on the end of atube in diameter without causing distortion, an air pressure of not morethan 16 lbs. per sq. in. should be employed.

It will be recognized from the foregoing that the objects of theinvention have been achieved insofar as a simple and inexpensive methodand means for tempering glass flares during the normal sequence ofoperations required to fabricate them has been provided whereby thefinished flares are strengthened sufliciently to enable them towithstand the mechanical and thermal shocks encountered during normalhandling and subsequent assembly operations and the resultant lossescaused by such breakage minimized. For example, the breakage due tomechanical shock caused by ejecting the finished flares from the machineinto the hopper has been reduced from a normal 5% and greater to lessthan 1%, while a reduction from 2% to less than 0.01% cracked flares dueto thermal shock on the sealing machine has been realized by using thismethod of flare manufacture. The method is also particularly suited forapplication on conventional type flaremaking machines generally employedin the industry by virtue of the fact that the normal sequence ofoperations of such machines requires that the glass be heated andcooled. Moreover, the tempering process and the ultimate strength of theflares can be controlled by apparatus which is simple and economical toinstall and operate.

Although a preferred embodiment of the invention has been illustrated inaccordance with the patent statutes, it will be understood that variousmodifications may be made in the details of construction, combinationand arrangement of parts without departing from the spirit and scope ofthe invention.

I claim:

1. In the manufacture of a glass flare, the process of forming a flangeon the end of a glass tube and tempering .said flange during the normalsequence of operations required to manufacture the flare which processcomprises, increasing the heat input to the part of said glass tube tobe flanged by an amount suflicient to increase the temperature thereofto a temperature above the softening point but below the working pointof the glass and above the temper-ature required to render itsufficiently plastic for the flange-forming operation, forming theheated part of said tube into a flange While maintaining the glass at apredetermined temperature above its annealing point, and immediatelythereafter abruptly cooling said flange below the strain point of theglass to permanently impart to the surface layers thereof apredetermined compressive stress.

2. In the manufacture of a glass flare, the process of forming a flangeon the end of a glass tube and tempering said flange during the normalsequence of operations required to manufacture the flare which processcomprises,

increasing the heat input to the end of said glass tube by an'amonntsufficient to increase the temperature thereof to a temperature abovethe softening point but below the working point of the glass and abovethe temperature re- 'the glass to a temperature below its strain pointwithout distorting said flange and permanently impart to said surfaces apredetermined compressive stress.

3. In the manufacture of a glass flare, the process of forming a flangeon the end of a glass tube and tempering said flange during the normalsequence of operations required to manufacture the flare which processcomprises, increasing the heat input to the end of said glass tube by anamount suflicient to increase the temperature thereof to a temperatureapproximately 200 C. above the softening point of the glass, formingsaid heated tube end into a flange Without reducing the temperaturethereof below the softening point of the glass, and immediatelythereafter rotating said glass tube about its longitudinal axis andapplying a controlled stream of compressed air to the surfaces of saidflange to cool the glass to a temperature below its strain point withoutdistorting said flange and permanently impart to said surfaces apredetermined compressive stress.

4. In the manufacture of a glass flare, the process of forming a flangeon the end of a glass tube and tempering said flange during the normalsequence of operations required to manufacture the flare which processcomprises, increasing the heat input to the end of said glass tube by anamount sumcient to increase the temperature thereof to a temperatureabove the softening point but below the working point of the glass andabove the temperature required to render it sufficiently plastic for theflange-forming operation, forming said heated tube end into a flangewhile maintaining the glass at a predetermined temperature above itsannealing point, and immediately thereafter rotating the glass tubeabout its longitudinal axis and passing said flange through a controlledair stream to cool the glass to a temperature below its strain pointabruptly without distorting said flange and permanently impart to saidsurfaces a permanent compressive stress of at least 75 kilograms persquare centimeter.

5. In combination with an automatic flare-making machine wherein alength of glass tubing is rotated about its longitudinal axis andindexed through a series of work stations including a preheating stationand a flangeforming station; apparatus for rapidly and uniformly coolingthe flanged portion of said tubing immediately after the preheating andflange-forming operations have been completed thereon and thus providingmeans for tempering said portion during the normal sequence ofoperations required to manufacture said flare comprising; means forholding said tubing; means for rotating said holding means; dispensingmeans secured to a stationary part of the machine at a tempering stationimmediately following the flange-forming station for applying a coolingmedium to the surfaces of the hot flanged portion of said tubing;conduit means for connecting said dispensing means with a pressurizedsupply of said cooling medium; and means in said conduit means forcontrolling the rate of flow of said cooling medium; said dispensingmeans comprising a pair of nozzles disposed in a com mon plane andcontoured to eject said cooling medium along said plane; said nozzlesbeing so oriented relative to one another and to said holding means thatsaid cooling medium is dispensed by said nozzles in a substantiallyuniplanar stream which impinges upon both sides of the flanged portionof said glass tubing when said tubing and holding means are located atsaid tempering station.

6. In combination with an automatic flare-making machine wherein alength of glass tubing is rotated about its longitudinal axis andindexed through a series of work stations including a preheating stationand a flangeforming station; apparatus for rapidly and uniformly coolingthe flanged portion of said tubing immediately after the preheating andflange-forming operations have been completed thereon and thus providingmeans for tempering said portion during the normal sequence ofoperations required to manufacture said flare comprising; means forholding said tubing; means for rotating said holding means; dispensingmeans secured to a stationary part of the machine at a tempering stationimmediately following the flange-forming station for applying a coolingmedium tothe surfaces of the hot flange formed on the end of said,tubing;'conduit meansfor connecting said dispensing means with apressurized supply of said cooling medium; means in said conduit meansfor controlling the rate of flow of said cooling medium; said dispensingmeans comprising a pair of nozzles arranged in a common plane andcontoured to dispense said cooling medium along said plane; therelationship of said nozzles to each other and to said holding meansbeing such that, when said tubing and holding means are located at saidtempering station, the lip of one of said nozzles is below said flangeand substantially parallel to the plane containing the rim of saidflange but spaced at predetermined distance therefrom, and the lip ofthe other of said nozzles is above said flange and disposed at an angleof approximately 60 with respect to the lip of the first said nozzle;and means in said conduit means for removing impurities from saidcooling medium, whereby said cooling medium is purified and thendispensed by said nozzles in a substantially uniplanar stream whichimpinges upon both sides of said flange and effects the rapid anduniform cooling thereof without contaminating the glass.

7. In combination with an automatic flare-making machine wherein alength of glass tubing is rotated about its longitudinal axis andindexed through a series of work stations including a' preheatingstation and a flangeforming station; apparatus for rapidly and uniformlycooling the flanged portion of said tubing immediately after thepreheating and flange-forming operations have been completed thereon andthus providing means for tempering said portion during the normalsequence of operations required to manufacture said flare comprising;means for holding said tubing; means for rotataing said holding means;dispensing means secured to a stationary part of the machine at atempering station immediately following the flange-forming station forapplying a cooling medium to the surfaces of the hot flange formed onthe end of said tubing; conduit means for connecting said dispensingmeans with a pressurized supply of said cooling medium; and means insaid conduit means for controlling the rate of flow of said coolingmedium; said dispensing means comprising a pair of nozzles that aredisposed in a common plane and have flat tips with substantiallyslot-like outlet orifices adapted and oriented to dispense said coolingmedium along said plane; said nozzles being so oriented with respect toeach other and to said holding means that, when said flanged tubing andholding means are located at said tempering station, the lip of one ofsaid nozzles is below said flange and sub; stantially parallel to theplane containing the rim of said flange but spaced a predetermineddistance therefrom, and the lip of the other of said nozzles is disposedabove said flange and defines an angle of approximately 60 with the lipof the first said nozzle; the plane containing said nozzles beingparallel to but slightly offset from the axis of the glass tubing whenthe latter is at said tempering station, whereby said cooling medium isdispensed by said nozzles in a substantially uniplanar stream whichimpinges upon both sides of said flange and is subsequently deflected bysaid tubing out of the machine.

References Qited in the file of this patent UNITED STATES PATENTSGrotefeld June 15,

1. IN THE MANUFACTURE OF A GLASS FLARE, THE PROCESS OF FORMING A FLANGEON THE END OF A GLASS TUBE AND TEMPERING SAID FLANGE DURING THE NORMALSEQUENCE OF OPERATIONS REQUIRED TO MANUFACTURE THE FLARE WHICH PROCESSCOMPRISES, INCREASING THE HEAT INPUT TO THE PART OF SAID GLASS TUBE TOBE FLANGED BY AN AMOUNT SUFFICIENT TO INCREASE THE TEMPERATURE THEREOFTO A TEMPERATURE ABOVE THE SOFTENING POINT BUT BELOW THE WORKING POINTOF THE GLASS AND ABOVE THE TEMPERATURE REQUIRED TO RENDER ITSUFFICIENTLY PLASTIC FOR THE FLANGE-FORMING OPERATION, FORMING THEHEATED PART OF SAID TUBE INTO A FLANGE WHILE MAINTAINING THE GLASS AT APREDETERMINED TEMPERATURE ABOVE ITS ANNEALING POINT, AND IMMEDIATELYTHEREAFTER ABRUPTLY COOLING SAID FLANGE BELOW THE STRAIN POINT OF THEGLASS TO PERMANENTLY IMPART TO THE SURFACE LAYERS THEREOF APREDETERMINED COMPRESSIVE STRESS.
 5. IN COMBINATION WITH AN AUTOMATICFLARE-MAKING MACHINE WHEREIN A LENGTH OF GLASS TUBING IS ROTATED ABOUTITS LONGITUDINAL AXIS AND INDEXED THROUGH A SERIES OF WORK STATIONSINCLUDING A PREHEATING STATION AND A FLANGEFORMING STATION; APPARATUSFOR RAPIDLY AND UNIFORMLY COOLING THE FLANGED PORTION OF SAID TUBINGIMMEDIATELY AFTER THE PREHEATING AND FLANGE-FORMING OPERATIONS HAVE BEENCOMPLETED THEREON AND THUS PROVIDING MEANS FOR TEMPERING SAID PORTIONDURING THE NORMAL SEQUENCE OF OPERA-